Heart talk: Emotional inner speech increases heart rate

In two pre-registered experiments (exp.1: n=44; exp.2: n=46), we investigated whether emotional inner speech has an effect on heart rate. Participants were asked to engage in sessions of either: positive inner speech, negative inner speech, or inner counting while their heart rate was monitored. Participants were lying on a bed and asked to remain still during the inner speech trials. Motion tracking was applied to control for body movement. Median heart rate across each inner speech session was analyzed and a significant difference was found between emotional inner speech and inner counting across both experiments. No difference between positive and negative inner speech was observed. Post-hoc analyses investigated the relationship between movement and heart rate increases and found an effect with a peak lag of approximately 14 seconds. Removing these effects did not change the effect that emotional inner speech had on heart rate. In line with previous literature, additional analyses showed that heart rate and respiration rate were linked. Including respiration rate as a variable in regression analyses did not alter the effect of emotion. The effect of emotional inner speech thus seems robust. No correlations between heart rate effects and measures of depression and rumination were observed.